Effects of historical agricultural crops on the soil microbiome of a living agricultural museum in the Sonoran Desert

Although soil has been a central piece in agricultural knowledge for most of recorded history, introductions of exotic plant assemblages can produce loss of soil quality, especially in more fragile ecosystems such as drylands. Here, we investigate the impact of indigenous and introduced plant assemblages associated with ethno-agricultural traditions of Tucson, AZ, on soil microbial communities using 16S rRNA gene (bacteria and archaea) and internal transcribed spacer region (fungi) metabarcoding. We found differences in soil microbial community diversity and composition across plant assemblages associated with ethno-agricultural traditions. However, we found the largest community structure differences between managed cultivated plots and not cultivated desert soils. Managed cultivated plots were characterized by higher diversity (23% increment for bacteria/archaea, and 40% for fungi) and a higher abundance of nitrifying bacteria (19% higher) and cellulolytic bacteria (39% higher) relative to minimally disturbed plots, suggesting higher rates of decomposition and nitrogen cycling. Given the observed influence of management on soil microbial communities, we conclude that efforts to build arid-specific sustainable agricultural solutions would benefit from the use of adapted plants that require minimal management.